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#![no_std]
#[cfg(test)]
extern crate std;
use core::fmt::{self, Display, Formatter, Write};
use core::str;
pub struct MarkupDisplay<E, T>
where
E: Escaper,
T: Display,
{
value: DisplayValue<T>,
escaper: E,
}
impl<E, T> MarkupDisplay<E, T>
where
E: Escaper,
T: Display,
{
pub fn new_unsafe(value: T, escaper: E) -> Self {
Self {
value: DisplayValue::Unsafe(value),
escaper,
}
}
pub fn new_safe(value: T, escaper: E) -> Self {
Self {
value: DisplayValue::Safe(value),
escaper,
}
}
pub fn mark_safe(mut self) -> MarkupDisplay<E, T> {
self.value = match self.value {
DisplayValue::Unsafe(t) => DisplayValue::Safe(t),
_ => self.value,
};
self
}
}
impl<E, T> Display for MarkupDisplay<E, T>
where
E: Escaper,
T: Display,
{
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
match self.value {
DisplayValue::Unsafe(ref t) => write!(
EscapeWriter {
fmt,
escaper: &self.escaper
},
"{}",
t
),
DisplayValue::Safe(ref t) => t.fmt(fmt),
}
}
}
pub struct EscapeWriter<'a, E, W> {
fmt: W,
escaper: &'a E,
}
impl<'a, E, W> Write for EscapeWriter<'a, E, W>
where
W: Write,
E: Escaper,
{
fn write_str(&mut self, s: &str) -> fmt::Result {
self.escaper.write_escaped(&mut self.fmt, s)
}
}
pub fn escape<E>(string: &str, escaper: E) -> Escaped<'_, E>
where
E: Escaper,
{
Escaped { string, escaper }
}
pub struct Escaped<'a, E>
where
E: Escaper,
{
string: &'a str,
escaper: E,
}
impl<'a, E> Display for Escaped<'a, E>
where
E: Escaper,
{
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
self.escaper.write_escaped(fmt, self.string)
}
}
pub struct Html;
macro_rules! escaping_body {
($start:ident, $i:ident, $fmt:ident, $bytes:ident, $quote:expr) => {{
if $start < $i {
$fmt.write_str(unsafe { str::from_utf8_unchecked(&$bytes[$start..$i]) })?;
}
$fmt.write_str($quote)?;
$start = $i + 1;
}};
}
impl Escaper for Html {
fn write_escaped<W>(&self, mut fmt: W, string: &str) -> fmt::Result
where
W: Write,
{
let bytes = string.as_bytes();
let mut start = 0;
for (i, b) in bytes.iter().enumerate() {
if b.wrapping_sub(b'"') <= FLAG {
match *b {
b'<' => escaping_body!(start, i, fmt, bytes, "<"),
b'>' => escaping_body!(start, i, fmt, bytes, ">"),
b'&' => escaping_body!(start, i, fmt, bytes, "&"),
b'"' => escaping_body!(start, i, fmt, bytes, """),
b'\'' => escaping_body!(start, i, fmt, bytes, "'"),
_ => (),
}
}
}
if start < bytes.len() {
fmt.write_str(unsafe { str::from_utf8_unchecked(&bytes[start..]) })
} else {
Ok(())
}
}
}
pub struct Text;
impl Escaper for Text {
fn write_escaped<W>(&self, mut fmt: W, string: &str) -> fmt::Result
where
W: Write,
{
fmt.write_str(string)
}
}
#[derive(Debug, PartialEq)]
enum DisplayValue<T>
where
T: Display,
{
Safe(T),
Unsafe(T),
}
pub trait Escaper {
fn write_escaped<W>(&self, fmt: W, string: &str) -> fmt::Result
where
W: Write;
}
const FLAG: u8 = b'>' - b'"';
#[cfg(test)]
mod tests {
use super::*;
use std::string::ToString;
#[test]
fn test_escape() {
assert_eq!(escape("", Html).to_string(), "");
assert_eq!(escape("<&>", Html).to_string(), "<&>");
assert_eq!(escape("bla&", Html).to_string(), "bla&");
assert_eq!(escape("<foo", Html).to_string(), "<foo");
assert_eq!(escape("bla&h", Html).to_string(), "bla&h");
}
}
|
